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Abstract:

Yoke-shaped sensors based on MgO-barrier magnetic tunnel junctions have been designed, fabricated, and studied; they show a good linear tunneling magnetoresistance (TMR) response. A nearly-perpendicular configuration of two ferromagnetic electrodes was set by two-step annealing together with shape anisotropy. The low-frequency noise characterization shows these yoke-shaped TMR sensors have relatively low magnetic 1/f noise. The field sensitivity is up to 27%/mT, while the field detectivity reaches 4.6 nT/Hz‾‾‾√ at 10 Hz and 460 pT/Hz‾‾‾√ at 1 kHz. These TMR sensors may be useful for applications such as biomagnetic detection.